Synthetic paper is known and available as a substitute for natural papers. The synthetic paper often has desirable properties that natural paper cannot provide. Synthetic papers have been used in areas to replace natural paper. One area of trouble, however, is ink adhesion to synthetic papers. Ink can be removed easily, especially thermal transfer ink. Coatings are often added to synthetic papers to improve their ink adhesion.
Synthetic paper can be used as labels by the adding an adhesive or heat seal layer to the synthetic paper. When used as shelving labels, synthetic paper with bar codes must be able to be read optically. When the synthetic paper is too glossy, the readings are difficult or impossible to make. Shelving labels are often placed on top of the previous label. As the price of products fluctuates, labels are normally placed on the previous label. The label needs to be opaque so there are no miss readings caused by the information on the buried label.
Labels are often printed with thermal transfer printing. Thermal transfer printing uses a heated stylus that heats wax-like ink on a transfer tape. The heated ink melts and is transferred to the labels. When the ink is applied to synthetic labels, the ink does not adhere well. In fact, the print will have good appearance (easily readable and with distinct images). However, when the ink is subjected to abrasion, such as by a finger nail, the ink is smudged or actually removed.
WO 99/58336, published in the name of Glopak Inc, relates to paper like sheet of plastic material. The paper like sheet feels like and has at least some of the properties of paper.
U.S. Pat. No. 4,986,866, issued in the name of Ohba et al, relates to a process for producing synthetic label paper. This label can be used for in-mold decorating of a container.
U.S. Pat. No. 5,616,384, issued to Goettmann et al, relates to a recyclable polymeric label paper. These materials may be used in blow molded containers in-mold without the use of an adhesive material.
U.S. Pat. No. 5,667,872, issued to Ohno et al, relates to synthetic paper with multi-layer structure and excellent printing.
A need exists for a synthetic paper which are useful with thermal transfer printing. This printing must permanent and not be easily removed by abrasion.